Method of decarbonating gas streams

Abstract

The present invention concerns a method of decarbonating a gas stream containing from 15% to 60% carbon dioxide, by passage of the said gas stream over a zeolitic agglomerate comprising at least one binder and at at least one zeolite, and having a mesoporous volume of between 0.02 cm 3 ·g −1 and 0.15 cm 3 ·g −1 and a mesoporous volume fraction of between 0.1 and 0.5, preferably between 0.15 and 0.45.

The invention claimed is: 
     
       1. A method of decarbonating a gas stream, the method comprising at least the steps of:
 a) supply of a gas stream containing 15% to 60% carbon dioxide, expressed as volume relative to the total volume of the gas stream, 
 b) passage of the gas stream over a zeolitic agglomerate, and 
 c) recovery of a gas stream depleted of CO 2 , 
 wherein the zeolitic agglomerate comprises at least one binder and at least one zeolite, and has a mesoporous volume between 0.02 cm 3 ·g −1  and 0.15 cm 3 ·g −1  and a mesoporous volume fraction between 0.1 and 0.5, 
 wherein the at least one binder is a mixture of clays comprising a montmorillonite clay and at least 50% by weight of a hormite clay, 
 wherein the zeolitic agglomerate is the form of beads having a size between 1.6 mm and 2.5 mm, 
 wherein the zeolitic agglomerate comprises crystals of zeolite(s) agglomerated with between 1% and 30% by weight, relative to the total weight of the zeolitic adsorbent, of the at least one binder, 
 wherein the at least one zeolite of the zeolitic agglomerate is a zeolite in the form of Faujasite type zeolitic crystals, selected from among X, LSX, MSX and Y zeolites and mixtures thereof, and 
 wherein the at least one zeolite of the zeolitic agglomerate is a zeolite in the form of crystals present in sodium form, with a sodium content expressed as sodium oxide (Na 2 O) greater than 9.0% by weight of oxide relative to the total weight of the agglomerate. 
 
     
     
       2. The method as claimed in  claim 1 , wherein the gas stream to be decarbonated contains from 15% to 60% carbon dioxide, by volume relative to the total volume of the gas stream. 
     
     
       3. The method as claimed in  claim 1 , wherein the gas stream to be decarbonated has a CO 2  content ranging from 15% to 60%, by volume relative to the total volume of the gas stream, and further contains one or more of the following gases:
 carbon monoxide (CO), generally from 20% to 50%, by volume relative to the total volume of the gas stream, 
 hydrogen (H 2 ), from 15% to 25% by volume relative to the total volume of the gas stream, 
 nitrogen (N 2 ) and/or argon (Ar), from 5% to 15% by volume relative to the total volume of the gas stream, 
 methane (CH 4 ), from 0.5% to 50% by volume relative to the total volume of the gas stream, 
 water (H 2 O), up to 4%, 
 hydrogen sulphide (H 2 S), from 80 ppmv to 100 ppmv. 
 
     
     
       4. The method as claimed in  claim 1 , the method being carried out at a temperature of between 0° C. and 100° C. 
     
     
       5. The method as claimed in  claim 1 , the method being carried out at a pressure of between 200 kPa and 400 kPa. 
     
     
       6. The method as claimed in  claim 1 , wherein the montmorillonite clay comprises bentonite. 
     
     
       7. The method as claimed in  claim 1 , wherein the hormite clay comprises attapulgite and/or sepiolite.